SOLAR SYSTEMSCHAPTER 21

definition

• Objects that revolve around a star• Major members

– Planets– Moons

• Minor members– Dwarf planets– Asteroids– Comets– meteoroids

What is a planet?(as of Aug. 2006)

• The IAU said that the definition for a planet is now officially known as "a celestial body that

• (a) is in orbit around a star

• (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a (nearly round) shape and

• (c) has cleared the neighborhood around its orbit."has cleared the neighborhood around its orbit." (not in a swarm of rocks) (not in a swarm of rocks)

Our solar system scoreboard

• Planets= 8• Moons= 167• Dwarf planets= 5• Asteroids= 536,000+• Comets= 3,062

Exosolarsystems

• Other solar systems• 661 new solar systems confirmed!• Over 3000 planets (exoplanets)

First discovered in 1995

Estimated over 50 BILLION

Earth like planets(habitable zone)

• Maybe 2?• Gliese D

– 6x more massive than earth “superearth”– In Libra– 20 lya

• HD 85512 b– In Vela– 26 lya

HOW DO ASTRONOMERS FIND NEW PLANETS???????

Radial Velocity

• Planets are detected by studying light shifts due to star wobbles

• Uses Doppler Effect– Red light moves AWAY– Blue light moves

TOWARDS

Astrometry

• Measures star wobbles from geometry

Transit method

• Planet blocks star (eclipse)• Light from star is lessen• Kepler mission

Optical detection

• Block star’s light out using a chronograph

List of exoplanets

• http://exoplanet.eu/catalog/

Exoplanet missions

• Kepler- launched 2009• Has found 77 planets so far

METHODS to find a new planet

• http://planetquest.jpl.nasa.gov/Planet_Finder/planetfinder.html

Other research

• LBT (large binocular telescope)• Keck telescopes (Hawaii)• Spitzer Space Telescope

– Infrared telescope

OUR SOLAR SYSTEM

Our solar systemOur solar system

The planets drawn The planets drawn to scaleto scale

INNER PLANETS

INNER PLANETS

• Terrestrial• Rocky• No rings• Smaller compared to Outer planets

MERCURY• No atmosphere• Temperatures fluctuate wildly• MESSANGER is currently orbiting

Mercury- has completed 282 orbits (so far!)

Sept. 29, 2009MESSANGER

Messenger 9/21/11

• Mapping surface of Mercury

MESSANGER IMAGEAug. 23. 2012

VENUS• THICK atmosphereTHICK atmosphere

– Hot!Hot!– Crushing pressureCrushing pressure

• Rotation is retrogradeRotation is retrograde– Sun rise in west; set in eastSun rise in west; set in east

Pancake volcanoes

MARS• Thin atm.• Windy• Surface similar to Earth

– Volcanoes– Old river valleys- where’s the water?– Best chance to find fossil (life?) in SS

Opportunity and Spirit

• http://marsrovers.jpl.nasa.gov/home/

CURIOSITYlanded Aug. 6, 2012

CURIOSITYCONFIRMS WATER ONCE FLOWED!!

Mars Moons

• Phobos • Deimos

Jovian Planets

• Outer planets• Large• Many moons• all have rings• Made of gas

JUPITER

• Often captures comets/asteroids– Shoemaker/Levy

comet (1994)

Jupiter’s Ring systemFeb. 2007

Jupiter’s New Moons

• Jupiter now has 63 known moons

• 23 moons were discovered in 2002-3 by Earth-based telescopes

http://solarsystem.nasa.gov/planets/profile.cfm?Object=Jupiter&Display=Moons

Saturn’s Rings• Made of Water ice

and dust• Sheppard moons

keep rings in place

Uranian Weirdness

A few of Uranus’s moons

MIRANDAPUCK

ARIELOBERON

Neptune• Very active weather

• Liquid nitrogen volcanoesLiquid nitrogen volcanoes• Cantaloupe terrainCantaloupe terrain• Underground oceans?Underground oceans?• Alien life?Alien life?

Triton-

Planet ?

• 2003 UB313 • Renamed Eris (Xena)

What is a planet?(as of Aug. 2006)

• The IAU said that the definition for a planet is now officially known as "a celestial body that

• (a) is in orbit around a star

• (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a (nearly round) shape and

• (c) has cleared the neighborhood around its orbit."has cleared the neighborhood around its orbit." (not in a swarm of rocks) (not in a swarm of rocks)

Pluto

• Dwarf planet

Lowell Observatorywhere Pluto was discovered

1939

Plutoids

• Dwarf planets beyond Neptune• Established in 2008

Planets, dwarf planets, plutoids

How many moons does Pluto have?

We’re on the way…

• New Horizons spacecraft was launched in Jan. 2006

• Will arrive at Pluto July 2015